The present invention relates to a reciprocating combustion engine comprising at least one cylinder in which a piston is reciprocatingly moveable and is connected by connecting rods to two parallel crank shafts that are connected by a toothing to one another such that they rotate in opposite directions.
Such a reciprocating internal combustion engine is known from German Patent Application 32 38 030 A1 and is described in the following with the aid of FIG. 8. The reciprocating internal combustion engine is shown in an exemplary fashion as a spark ignition engine (otto engine) and has a cylinder 2 in which a piston 4 is working. The intake manifold 6 opens into the cylinder head 8 whereby in the mouth of the intake manifold at the cylinder head an intake valve 10 is provided. Furthermore, an exhaust manifold 12 is represented having a mouth at the cylinder head 8 in which the exhaust valve 14 is positioned.
In the intake manifold a throttle 16 is positioned, and downstream of the throttle 16 the fuel injector 18 is positioned. In the cylinder head spark plugs 20 are also positioned which extend into the combustion chamber.
A control device 22 is provided for controlling the spark plugs 20 and the fuel injector 18 whereby the input terminals of the control device are supplied in a manner known to a person skilled in the art by signals of different sensors for detecting the operating parameters of the internal combustion engine. The control device 22 then computes control signals for controlling injection and ignition.
In the crankcase 28 of the internal combustion engine two parallel crankshafts 30 and 32 are arranged which, relative to the axis of piston movement, are symmetrically arranged and are connected to one another by a meshing toothing (gear wheel) 34 so that they rotate in opposite directions.
Each one of the crankshafts 30 and 32 is connected by a connecting rod 36, 38 to the piston 4. The underside of the piston has spaced apart bearings 40 and 42 for supporting the connecting rods 36 and 38, whereby the bearings 40 and 42 are spaced in the direction of spacing between the crankshafts 30 and 32. As an alternative, the connecting rods can also be coaxially connected to the piston.
A special feature of the double crankshaft drive will be explained with the aid of FIG. 9. The ordinate of the diagram shows the piston stroke H and the abscissa shows the angle of rotation of the crankshafts, relative to the bottom dead center UT of the piston. This means that between the two bottom that center positions a 360.degree. rotation of the crankshaft takes place.
The dashed line shows the behavior of a conventional crankshaft drive in which the crankshaft is arranged centrally below the piston. The top dead center OT.sub.1 of the piston in the conventional crankshaft drive is located exactly between the two bottom UT positions, i.e., at 180.degree. angle of rotation of the crankshaft.
For the double crankshaft drive according to FIG. 8, in which the two crankshafts 30 and 32 are symmetrically offset relative to the center of the piston 4, a curve shown in solid lines results. Starting from the UT position of the piston the crankshafts 30 and 32 rotate in opposite directions whereby the left crankshaft of FIG. 1 rotates in the clockwise direction by less that 180.degree. until the top dead center OT.sub.2 of the piston has been reached and, subsequently, upon rotation by more than 180.degree., will reach again the bottom dead center UT. In a four stroke method, the intake stroke and the working stroke, in comparison to conventional crankshaft drive have available, an increased angular range and thus a longer time period so that filling and load conversion are improved.
One special feature of the double crankshaft drive is that the connecting rods 36 and 38 are rotated outwardly from the axis of the piston. The wall of the cylinder 2 can thus be elongated in the direction toward the crankshaft drive only to a limited amount. This accordingly limits the stroke length that can be realized for the provided constructive space and thus determines the constructive height of the engine.
It is an object of the present invention to embody a reciprocating internal combustion engine of the aforementioned kind such that for a given constructive height an increased stroke is realized.